1. Field of the Invention
The present invention relates to disc brake systems and more particularly to an improved technique for joining a wheel hub and brake rotor to reduce rotor distortion and improve cooling airflow.
2. Description of the Related Art
It is desirable to lower overall corner unit weight while improving performance.
The state of the art in wheel end designs has progressed to a point where the brake rotor is an easily serviced component that is held in place by clamping it between the wheel and wheel hub. It is inherent in this type of design that the unequal clamp load created by tightening the wheel lug nuts distorts the brake rotor which increases the mounted lateral run out (LRO) of the brake rotor. The typical engineering problem associated with high LRO is brake roughness.
U.S. Pat. No. 6,988,598 among others, allows the rotor to slide axially while remaining rotationally fixed to the wheel upon brake actuation alleviating some of the problem.
A recent salutary advance provides solutions to these problems by fixing the rotor to the hub flange outside the wheel-to-hub flange bolted joint to reduce mounted rotor distortion caused by wheel clamp load. In this design, the rotor is fixed to the outboard side of the hub (the side of the hub facing away from the vehicle to which the wheel typically mounts) and retains the “hat” feature common in disc brake rotors.
Another recent and noteworthy advance corrugates the hat portion of the rotor to stiffen it and reduce the transmission of strain energy from the wheel mounting surface to the brake plate.
The high operating temperatures of the brake rotor can also lead to thermal distortion of the brake plates. This distortion can eventually lead to brake roughness. Allowing more airflow around the brake rotor may lead to reduced operating temperatures and therefore less distortion.